Charge-trap type non-volatile memory devices and related methods

ABSTRACT

Methods of forming a non-volatile memory device may include forming a tunnel insulating layer on a semiconductor substrate and forming a charge-trap layer on the tunnel insulating layer. A trench may then be formed extending through the tunnel insulating layer and the charge-trap layer and into the semiconductor substrate so that portions of the charge-trap layer and the tunnel insulating layers remain on opposite sides of the trench. A device isolation layer may be formed in the trench, and a blocking insulating layer may be formed on the device isolation layer and on remaining portions of the charge-trap layer. A gate electrode may be formed on the blocking insulating layer, and the blocking insulating layer and remaining portions of the charge-trap layer may be patterned to provide a blocking insulating pattern and a charge-trap pattern between the gate electrode and the semiconductor substrate. Related structures are also discussed.

RELATED APPLICATIONS

This U.S. non-provisional patent application claims priority under 35U.S.C. § 119 of Korean Patent Application No. 2006-37805, filed on Apr.26, 2006, the disclosure of which is hereby incorporated herein byreference in its entirety.

FIELD OF THE INVENTION

The present invention relates generally to semiconductor devices, andmore particularly, to non-volatile memory devices and methods of formingthe same.

BACKGROUND

Non-volatile memory devices may be classified into two basic types,floating gate type non-volatile memory devices, and charge-trap typenon-volatile memory devices. A floating gate type non-volatile memorydevice stores electrical charges in a floating gate as free carriers,and a charge-trap type non-volatile memory device stores electricalcharges in spatially-isolated traps within a charge-trap layer.

A floating gate type non-volatile memory device may provide lowerintegration (device density) because of a height of a floating gate.Moreover, as a floating gate type non-volatile memory semiconductordevice is more highly integrated, distances between floating gates areshortened, and defective operations may occur due to an interferenceeffect between the floating gates. Also, since a floating gate typenon-volatile memory device stores electrical charges as free carriers, afloating gate type non-volatile memory device may require a thick tunnelinsulating layer as compared to a charge-trap type non-volatile memorydevice. Accordingly, a floating gate type non-volatile memory device mayconsume more power than a charge-trap type non-volatile memory device.

An example of a conventional charge-trap type non-volatile memory deviceis a silicon-oxide-nitride-oxide-silicon (SONOS) memory device. A SONOSmemory device uses polysilicon as a gate electrode, silicon oxide as atunnel-insulating layer and as a blocking insulating layer, and siliconnitride as a charge-trap layer between two insulating layers.

Electrical charges that are once trapped in the silicon nitride layerproviding charge-trapping may not significantly move horizontally.Accordingly, at least two adjacent memory cell transistors may share acharge-trap layer in a conventional SONOS memory device. Recent researchhas revealed, however, that some charge in the silicon nitride layer maymove horizontally. Horizontal movement of electrical charge may causeloss of charge, thereby changing a threshold voltage of a memory celltransistor.

In a conventional SONOS memory device, when an erase operation isperformed by discharging electrical charge trapped in the charge-traplayer to a semiconductor substrate, a negative voltage may be applied toword lines. Here, since both of the blocking insulating layer and thetunnel-insulating layer are formed of silicon oxide, dielectricconstants of the two layers may be the same, and thus almost the sameelectric field may be provided at the two insulating layers, causingback tunneling. For this reason, charge trapped in the charge-trap layermay not be completely discharged, and may stay in the charge-trap layer.To reduce occurrence of this defective erase operation, the blockinginsulating layer may be made of a high-dielectric material having agreater dielectric constant than that of silicon oxide, and the gateelectrode may be made of a material having a higher work function thanthat of polysilicon. When the blocking insulating layer formed of thehigh dielectric material is etched, however, the blocking insulatinglayer may be damaged by a plasma generated during dry-etching, which maygenerate defects on a sidewall of the blocking insulating layer.Problems such as breakdown voltage drop may thus result, therebyreducing reliability of the charge-trap type non-volatile memory device.

SUMMARY

According to some embodiments of the present invention, a method offorming a non-volatile memory device may include forming a tunnelinsulating layer on a semiconductor substrate, and forming a charge-traplayer on the tunnel insulating layer. A trench may be formed extendingthrough the tunnel insulating layer and the charge-trap layer and intothe semiconductor substrate so that portions of the charge-trap layerand the tunnel insulating layers remain on opposite sides of the trench.A device isolation layer may be formed in the trench, and a blockinginsulating layer may be formed on the device isolation layer and onremaining portions of the charge-trap layer. A gate electrode may beformed on the blocking insulating layer, and the blocking insulatinglayer and remaining portions of the charge-trap layer may be patternedto provide a blocking insulating pattern and a charge-trap patternbetween the gate electrode and the semiconductor substrate.

The blocking insulating layer may include a layer of a material having adielectric constant higher than that of silicon oxide. The gateelectrode may include a material having a work function higher than thatof polysilicon, and more particularly, the gate electrode may include ametal.

Before forming the trench, a passivation layer may be formed on thecharge-trap layer and a planarization stop layer may be formed on thepassivation layer, so that forming the trench further includes formingthe trench through the planarization stop layer and the passivationlayer. Moreover, forming the device isolation layer may include formingan insulating layer on remaining portions of the planarization stoplayer and in the trench, planarizing the insulating layer to expose theplanarization stop layer while maintaining portions of the insulatinglayer in the trench, and removing the planarization stop layer and thepassivation layer. In addition, removing the passivation layer mayinclude removing a portion of the device isolation layer.

The charge-trap pattern may be recessed relative to a surface of thedevice isolation layer opposite the substrate. The semiconductorsubstrate may include a cell array region and a peripheral circuitregion, and before forming the blocking insulating layer, portions ofthe charge-trap layer on the peripheral circuit region of thesemiconductor substrate may be removed while maintaining portions of thecharge-trap layer on the cell array region of the semiconductorsubstrate. In addition, before patterning the blocking insulating layerand remaining portions of the charge-trap layer, spacers may be formedon sidewalls of the gate electrode, and patterning the blockinginsulating layer and remaining portions of the charge-trap layer mayinclude patterning the blocking insulating layer and remaining portionsof the charge-trap layer using the spacers as an etch mask.

According to some other embodiments of the present invention, a methodof forming a non-volatile memory device may include forming a deviceisolation layer on portions of a semiconductor substrate separatingfirst and second active regions of the semiconductor substrate onopposite sides of the device isolation layer. First and second tunnelinsulating patterns may be formed on the first and second active regionsof the semiconductor substrate, and first and second charge-trappatterns may be formed on the respective first and second tunnelinsulating patterns. Moreover, portions of the device isolation layerbetween the first and second charge-trap patterns may be free of thefirst and second charge-trap patterns, and a word line may be formed onthe first and second charge-trap patterns and on portions of the deviceisolation layer between the first and second charge-trap patterns.

In addition, a blocking insulating layer may be formed on the first andsecond charge-trap patterns and on the device isolation layer so thatthe blocking insulating layer is between the word line and the first andsecond charge-trap patterns and between the word line and the deviceisolation layer. More particularly, the tunnel insulating layer mayinclude a layer of a first insulating material having a first dielectricconstant, the blocking insulating layer may include a layer of a secondinsulating material having a second dielectric constant, and the firstdielectric constant may be less than the second dielectric constant.

Each of the first and second charge-trap patterns may have a respectivesidewall directly adjacent respective sidewalls of the device isolationlayer. The word line may include a material having a work functionhigher than that of polysilicon, and more particularly, the word linemay include a metal. A surface of the device isolation layer oppositethe semiconductor substrate may extend at least as far from thesemiconductor substrate as surfaces of the charge-trap patterns oppositethe semiconductor substrate. In other words, the charge-trap patternsmay be recessed relative to the device isolation layer.

The semiconductor substrate may include a cell array region and aperipheral circuit region and the word line may be on the cell arrayregion. In addition, a peripheral circuit gate insulating layer may beformed on a peripheral circuit region of the semiconductor substrate,and a peripheral circuit gate electrode may be formed on the peripheralcircuit gate insulating layer so that the peripheral circuit gateinsulating layer is between the peripheral circuit gate electrode andthe peripheral circuit region of the semiconductor substrate. Moreover,a separation between the peripheral circuit gate electrode and theperipheral circuit region of the semiconductor substrate may be lessthan a separation between the word line and the first and second activeregions of the semiconductor substrate.

First and second selection gate insulating patterns may be formed on thefirst and second active regions spaced apart from the first and secondtunnel insulating patterns. In addition, a selection line may be formedon the first and second selection gate insulting patterns and onportions of the device isolation layer between the first and secondselection gate insulating patterns. Moreover, a separation between theselection line and the first and second active regions of thesemiconductor substrate may be less than a separation between the wordline and the first and second active regions of the semiconductorsubstrate. Spacers may also be formed on sidewalls of the word line, andthe first and second charge-trap patterns may be between the spacers andthe semiconductor substrate in a direction perpendicular with respect toa surface of the semiconductor substrate.

According to still other embodiments of the present invention, anon-volatile memory device may include a semiconductor substrate and adevice isolation layer on the semiconductor substrate separating firstand second active regions of the semiconductor substrate on oppositesides of the device isolation layer. First and second tunnel insulatingpatterns may be on the first and second active regions, and first andsecond charge-trap patterns may be on the respective first and secondtunnel insulating patterns. More particularly, portions of the deviceisolation layer between the first and second charge-trap patterns may befree of the first and second charge-trap patterns. A word line may alsobe on the first and second charge-trap patterns and on portions of thedevice isolation layer between the first and second charge-trappatterns.

In addition, a blocking insulating layer may be between the word lineand the first and second charge-trap patterns and between the word lineand the device isolation layer. Moreover, the tunnel insulating layermay include a layer of a first insulating material having a firstdielectric constant, the blocking insulating layer may include a layerof a second insulating material having a second dielectric constant, andthe first dielectric constant may be less than the second dielectricconstant.

Each of the first and second charge-trap patterns may have a respectivesidewall directly adjacent respective sidewalls of the device isolationlayer. The word line may include a material having a work functionhigher than that of polysilicon, and more particularly, the word linemay include a material including metal. A surface of the deviceisolation layer opposite the semiconductor substrate may extend at leastas far from the semiconductor substrate as surfaces of the charge-trappatterns opposite the semiconductor substrate.

The semiconductor substrate may include a cell array region and aperipheral circuit region and the word line may be on the cell arrayregion. In addition, a peripheral circuit gate insulating layer may beon a peripheral circuit region of the semiconductor substrate, and aperipheral circuit gate electrode may be on the peripheral circuit gateinsulating layer so that the peripheral circuit gate insulating layer isbetween the peripheral circuit gate electrode and the peripheral circuitregion of the semiconductor substrate. Moreover, a separation betweenthe peripheral circuit gate electrode and the peripheral circuit regionof the semiconductor substrate may be less than a separation between theword line and the first and second active regions of the semiconductorsubstrate. In addition, spacers may be provided on sidewalls of theperipheral circuit gate electrode, and the peripheral circuit gateinsulating layer may be between the spacers and the semiconductorsubstrate in a direction parallel with respect to a surface of thesemiconductor substrate.

First and second selection gate insulating patterns on the first andsecond active regions may be spaced apart from the first and secondtunnel insulating patterns, and a selection line may be on the first andsecond selection gate insulting patterns and on portions of the deviceisolation layer between the first and second selection gate insulatingpatterns. Moreover, a separation between the selection line and thefirst and second active regions of the semiconductor substrate may beless than a separation between the word line and the first and secondactive regions of the semiconductor substrate. Spacers may be onsidewalls of the selection line, and the first and second selection gateinsulating patterns may be between the spacers and the semiconductorsubstrate in a direction parallel with respect to a surface of thesemiconductor substrate.

In addition, spacers may be provided on sidewalls of the word line, andthe first and second charge-trap patterns may be between the spacers andthe semiconductor substrate in a direction perpendicular with respect toa surface of the semiconductor substrate.

Some embodiments of the present invention may provide charge-trap typenon-volatile memory devices having improved reliability, and a methodsof forming the same.

According to some embodiments of the present invention, a charge-traptype non-volatile memory device may include a semiconductor substrateand a tunnel insulating layer and a charge-trap layer sequentiallystacked on the semiconductor substrate. A device isolation layer maypass through portions of the charge-trap layer, the tunnel insulatinglayer, and the semiconductor substrate to define an active region. Aword line may be formed across the semiconductor substrate and mayintersect the device isolation layer. A blocking insulating layer may beinterposed between the word line and the charge-trap layer and betweenthe word line and the device isolation layer.

The blocking insulating layer may be formed of a material having ahigher dielectric constant than that of silicon oxide. The gateelectrode layer may be a metal containing layer. The gate electrodelayer may be formed of a material having a higher work function thanthat of polysilicon. The device isolation layer may have a top surfacehigher than or on the same level as a top surface of the charge-traplayer.

The semiconductor substrate may include a cell array region and aperipheral circuit region, and the word line may be placed in the cellarray region. The device may further include a peripheral circuit gateinsulating layer and a peripheral circuit gate electrode sequentiallystacked on the semiconductor substrate in the peripheral circuit region.Here, the peripheral circuit gate insulating layer may include at leastone of the blocking insulating layer and the tunnel insulating layer,but not include the charge-trap layer.

The device may further include a selection line placed on thesemiconductor substrate in the cell array region with the selection linebeing parallel to the word line, and a selection gate insulating layerinterposed between the selection line and the semiconductor substrate.The selection gate insulating layer may include at least one of theblocking insulating layer and the tunnel insulating layer, but not thecharge-trap layer.

The device may further include a spacer covering a sidewall of the wordline, and the blocking insulating layer, the charge-trap layer, and thetunnel insulating layer may have sidewalls aligned with an outer lowerend of the spacer. The blocking insulating layer may contact a bottomsurface of the spacer.

The device may also include a spacer covering a sidewall of theperipheral circuit gate electrode, and the peripheral circuit gateinsulating layer may contact a bottom surface of the spacer and have asidewall aligned with an outer lower end of the spacer.

The device may further include a spacer covering a sidewall of theselection line. The selection gate insulating layer may contact a bottomsurface of the spacer and may have a sidewall aligned with an outerlower end of the spacer.

According to some other embodiments of the present invention, a methodof forming a charge-trap type non-volatile memory device may includesequentially forming a tunnel insulating layer and a charge-trap layeron a semiconductor substrate. Portions of the charge-trap layer, thetunnel insulating layer, and the semiconductor substrate may be etchedto form a trench, and a device isolation layer may be formed to fill thetrench. A blocking insulating layer may be formed on an entire surfaceof the semiconductor substrate including the device isolation layer. Agate electrode layer may be formed on the blocking insulating layer, andthe gate electrode layer may be patterned to form a gate electrode onthe blocking insulating layer. The blocking insulating layer, thecharge-trap layer and the tunnel insulating layer may be sequentiallypatterned to form a tunnel insulating layer pattern, a charge-trap layerpattern and a blocking insulating layer pattern that are sequentiallystacked.

Before the etching of the portions of the charge-trap layer, the tunnelinsulating layer and the semiconductor substrate to form the trench, apassivation layer may be formed on the charge-trap layer, and aplanarization stop layer may be formed on the passivation layer. Here,forming the trench may include etching portions of the planarizationstop layer, the passivation layer, the charge-trap layer, the tunnelinsulating layer, and the semiconductor substrate.

Forming the device isolation layer may include forming an insulatinglayer on an entire surface of the semiconductor substrate including thetrench to fill the trench with the insulating layer and performing aplanarization process on the insulating layer to expose theplanarization stop layer and simultaneously form a temporary deviceisolation layer within the trench. The temporary device isolation layermay have a same height as that of the planarization stop layer. Aportion of a top surface of the temporary device isolating layer may berecessed to partially expose a side surface of the planarization stoplayer and to simultaneously form the device isolation layer within thetrench. The planarization stop layer and the passivation layer may thenbe removed.

Removing the passivation layer may include removing a portion of a topsurface of the device isolation layer. The semiconductor substrate mayinclude a cell array region and a peripheral circuit region, and thecharge-trap layer in the peripheral region may be removed before theforming the blocking insulating layer.

In addition, a spacer may be formed covering a sidewall of the gateelectrode before sequentially patterning the blocking insulating layer,the charge-trap layer, and the tunnel insulating layer. The sequentialpatterning of the blocking insulating layer, the charge-trap layer andthe tunnel insulating layer to form the tunnel insulating layer pattern,the charge-trap layer pattern and the blocking insulating layer patternthat are sequentially stacked may use the spacer and the gate electrodeas an etch mask.

BRIEF DESCRIPTION OF THE FIGURES

The accompanying figures are included to provide a further understandingof embodiments of the present invention, and are incorporated in andconstitute a part of this specification. The drawings illustrateembodiments of the present invention and, together with the description,serve to explain principles of the present invention. In the figures:

FIGS. 1 through 7, and FIGS. 9 through 11 are perspective viewsillustrating operations of forming a charge-trap type non-volatilememory device according to some embodiments of the present invention;and

FIG. 8 is a perspective view illustrating operations of forming acharge-trap type non-volatile memory device according to otherembodiments of the present invention.

DETAILED DESCRIPTION

The present invention is described more fully hereinafter with referenceto the accompanying drawings, in which embodiments of the presentinvention are shown. This invention may, however, be embodied in manydifferent forms and should not be construed as limited to theembodiments set forth herein. Rather, these embodiments are provided sothat this disclosure will be thorough and complete, and will fullyconvey the scope of the present invention to those skilled in the art.In the drawings, the sizes and relative sizes of layers and regions maybe exaggerated for clarity. Like numbers refer to like elementsthroughout.

It will be understood that when an element or layer is referred to asbeing “on”, “connected to” or “coupled to” another element or layer, itcan be directly on, connected or coupled to the other element, or layeror intervening elements or layers may be present. In contrast, when anelement is referred to as being “directly on,” “directly connected to”or “directly coupled to” another element or layer, there are nointervening elements or layers present. As used herein, the term“and/or” includes any and all combinations of one or more of theassociated listed items.

It will be understood that, although the terms first, second, third etc.may be used herein to describe various elements, components, regions,layers and/or sections, these elements, components, regions, layersand/or sections should not be limited by these terms. These terms areonly used to distinguish one element, component, region, layer orsection from another region, layer or section. Thus, a first element,component, region, layer or section discussed below could be termed asecond element, component, region, layer or section without departingfrom the teachings of the present invention.

Spatially relative terms, such as “beneath”, “below”, “lower”, “above”,“upper” and the like, may be used herein for ease of description todescribe one element or feature's relationship to another element(s) orfeature(s) as illustrated in the figures. It will be understood that thespatially relative terms are intended to encompass differentorientations of the device in use or operation in addition to theorientation depicted in the figures. For example, if the device in thefigures is turned over, elements described as “below” or “beneath” otherelements or features would then be oriented “above” the other elementsor features. Thus, the exemplary term “below” can encompass both anorientation of above and below. The device may be otherwise oriented(rotated 90 degrees or at other orientations) and the spatially relativedescriptors used herein interpreted accordingly. Also, as used herein,“lateral” refers to a direction that is substantially orthogonal to avertical direction.

The terminology used herein is for the purpose of describing particularembodiments only, and is not intended to be limiting of the presentinvention. As used herein, the singular forms “a”, “an” and “the” areintended to include the plural forms as well, unless the context clearlyindicates otherwise. It will be further understood that the terms“comprises” and/or “comprising,” when used in this specification,specify the presence of stated features, integers, steps, operations,elements, and/or components, but do not preclude the presence oraddition of one or more other features, integers, steps, operations,elements, components, and/or groups thereof.

Example embodiments of the present invention are described herein withreference to cross-section illustrations that are schematicillustrations of idealized embodiments (and intermediate structures) ofthe invention. As such, variations from the shapes of the illustrationsas a result, for example, of manufacturing techniques and/or tolerances,are to be expected. Thus, embodiments of the present invention shouldnot be construed as limited to the particular shapes of regionsillustrated herein but are to include deviations in shapes that result,for example, from manufacturing. For example, an implanted regionillustrated as a rectangle will, typically, have rounded or curvedfeatures and/or a gradient of implant concentration at its edges ratherthan a binary change from implanted to non-implanted region. Likewise, aburied region formed by implantation may result in some implantation inthe region between the buried region and the surface through which theimplantation takes place. Thus, the regions illustrated in the figuresare schematic in nature and their shapes are not intended to illustratethe actual shape of a region of a device and are not intended to limitthe scope of the present invention.

Unless otherwise defined, all terms (including technical and scientificterms) used herein have the same meaning as commonly understood by oneof ordinary skill in the art to which this invention belongs.Accordingly, these terms can include equivalent terms that are createdafter such time. It will be further understood that terms, such as thosedefined in commonly used dictionaries, should be interpreted as having ameaning that is consistent with their meaning in the presentspecification and in the context of the relevant art, and will not beinterpreted in an idealized or overly formal sense unless expressly sodefined herein. All publications, patent applications, patents, andother references mentioned herein are incorporated by reference in theirentirety.

FIGS. 1 through 7 and FIGS. 9 through 11 are perspective viewsillustrating operations of forming a charge-trap type non-volatilememory device according to some embodiments of the present invention.

Referring to FIG. 1, a tunnel insulating layer 3 and a charge-trap layer5 are sequentially formed on a semiconductor substrate 1 including adriving region and a memory region. The tunnel insulating layer 3 may bea silicon oxide layer formed by thermal oxidation. The tunnel insulatinglayer 3 may be a layer of a high dielectric material such as a hafniumoxide layer, an aluminum oxide layer, a hafnium aluminum oxide layer,and/or a zirconium oxide layer. The charge-trap layer 5 for example maybe a silicon nitride layer (Si_(x)N_(y)). A ratio of silicon to nitrogenof the silicon nitride layer (Si_(x)N_(y)) may vary. The charge-traplayer 5 may be formed, for example, using chemical vapor deposition(CVD). The memory region refers to a region where transistors includingthe charge-trap layer are formed, that is, a region where cell memorytransistors (or word lines) are formed. The driving region may be aregion where transistors that do not include the charge-trap layer (forexample, driving transistors for driving the cell memory transistors)are formed. The driving region may be a peripheral circuit region or aregion where a selection line (such as a string selection line or aground selection line) is formed in a NAND type non-volatile memorydevice.

Referring to FIG. 2, a passivation layer 7 and a planarization stoplayer 9 may be sequentially formed on the charge-trap layer 5. Theplanarization stop layer 9 may be formed of a material having an etchselectivity with respect to a device isolation layer to be formed later.The planarization stop layer 9 may be, for example, a silicon nitridelayer. The passivation layer 7 may protect the charge-trap layer 5, andmay release stress between the planarization stop layer 9 and thecharge-trap layer 5. The passivation layer 7 may be formed of a materialhaving an etch selectivity with respect to the charge-trap layer 5 (suchas a medium temperature oxide (MTO)).

Referring to FIG. 3, a photoresist pattern (not shown) may be formed onthe planarization stop layer 9. Portions of the planarization stop layer9, the passivation layer 7, the charge-trap layer 5, the tunnelinsulating layer 3, and the semiconductor substrate 1 may besequentially etched using the photoresist pattern (not shown) as an etchmask, thereby forming trenches 11 and simultaneously forming tunnelinsulating patterns 3 a, charge-trap patterns 5 a, passivation layerpatterns 7 a and planarization stop patterns 9 a in sequence. Althoughthe trench 11 of a line type may be formed across the driving region andthe memory region as shown in FIG. 3, the trench can be formed invarious other manners. After the trench 11 is formed, the photoresistpattern (not shown) is removed.

Referring to FIG. 4, a insulating layer (not shown) may be formed on anentire surface of the semiconductor substrate 1 including the trenches11 such that the trenches 11 are filled with the insulating layer (notshown). Various types of oxide layers may be used as the insulatinglayer, such as a high density plasma (HDP) oxide layer, an undopedsilicate glass, or the like. Before the insulating layer (not shown) isformed, a thermal oxidation process may be performed on thesemiconductor substrate 1 including the trenches 11 to remove etchingdamage caused by the trench formation and to form a conformal thermaloxide layer on inner walls of the trenches 11. A planarization processmay be performed on the insulating layer (not shown) to expose theplanarization stop patterns 9 a and to simultaneously form temporarydevice isolation layers 13 in the trenches 11.

Referring to FIG. 5, upper portions of the temporary device isolationlayers 13 may be partially recessed to expose at least portions ofsidewalls of the planarization stop patterns 9 a. Here, the sidewalls ofthe planarization stop patterns 9 a may be entirely exposed, whilesidewalls of the passivation layer patterns 7 a are not exposed. In sucha manner, device isolation layers 13 a are formed.

Referring to FIGS. 5 and 6, the planarization stop patterns 9 a may beremoved to expose the passivation layer patterns 7 a. When theplanarization stop pattern 9 a is formed of silicon nitride, phosphoricacid may be used to remove the planarization stop pattern 9 a. Then, theexposed passivation layer patterns 7 a may be removed. When thepassivation layer patterns 7 a and the device isolation layers 13 a areformed of a same oxide based material, upper portions of the deviceisolation layers 13 a may be partially removed when the passivationlayer patterns 7 a are removed. Each of the device isolation layers 13 bformed as discussed above may have a top surface higher than or on thesame level as a top surface of the charge-trap pattern 5 a. Accordingly,concentration of an electric field at an edge of an active region may bereduced during device operation, so that current leakage may be reduced.

Accordingly, charge-trap patterns 5 a may be self-aligned withrespective device isolation layers 13 b.

Referring to FIG. 7, a mask pattern 15 may be formed on thesemiconductor substrate 1 including the device isolation layers 13 b.The mask pattern 15 may expose the driving region while covering thememory region. The mask pattern 15 may be, for example, a photoresistpattern. Portions of the charge-trap patterns 5 a exposed in the drivingregion may be removed using the mask pattern 15 as an etch mask. Thus,charge-trap patterns 5 b may remain on the memory region, and the tunnelinsulating patterns 3 a may be exposed in the driving region.

According to other embodiments of the present invention, as illustratedin FIG. 8, portions of the tunnel insulating patterns 3 a exposed in thedriving region may also be removed, using the mask pattern 15 as an etchmask, thereby exposing portions of the semiconductor substrate 1 in thedriving region.

Referring to FIGS. 7 and 9, the mask pattern 15 may be removed in astate where the tunnel insulating patterns 3 a are exposed in thedriving region. Thus, the charge-trap patterns 5 b may be exposed in thememory region. Then, a blocking insulating layer 17 and a gate electrodelayer 19 may be sequentially formed on an entire surface of thesemiconductor substrate 1. The blocking insulating layer 17 may beformed of a material having a higher dielectric constant than that ofsilicon oxide. The blocking insulating layer 17, for example, may be alayer of a high dielectric material such as hafnium oxide, aluminumoxide, hafnium aluminum oxide, and/or zirconium oxide. The gateelectrode layer 19 may be formed of a material having a higher workfunction than that of polysilicon, and may be, for example, a metalcontaining layer. The gate electrode layer 19, for example, may includeTaN, WN and/or W.

Referring to FIGS. 9 and 10, a capping layer pattern (not shown) may beformed on the gate electrode layer 19, and the gate electrode layer 19may be etched using the capping layer pattern as an etch mask. Thus, adriving gate line 19 b may be formed on the driving region and a wordline 19 a may be formed on the memory region at the same time. Thedriving gate line 19 b may be a peripheral circuit gate electrode, astring selection line, and/or a ground selection line.

Referring to FIGS. 10 and 11, a spacer layer (not shown) may beconformally formed on an entire surface of the semiconductor substrate 1including the driving gate line 19 b and the word line 19 a. Then, thespacer layer may be anisotropically etched to form first spacers 21 aand a second spacers 21 b that cover sidewalls of the word line 19 a andthe driving gate line 19 b, respectively. The spacers 21 a and 21 b mayalso cover sidewalls of a capping layer pattern(s) (not shown). Then,the blocking insulating layer 17, the charge-trap patterns 5 b and thetunnel insulating patterns 3 a may be etched using the lines 19 a and 19b and the spacers 21 a and 21 b as etch masks, to expose portions of thesemiconductor substrate 1 and the device isolation layers 13 b that areadjacent to each of the lines 19 a and the 19 b. Thus, in the drivingregion, driving gate insulating layers 23 b, each including a tunnelinsulating pattern 3 b and a driving blocking insulating pattern 17 bthat are sequentially stacked, may be formed under the driving gate line19 b and the second spacers 21 b. At the same time in the memory region,memory gate insulating layers 23 a, each including a tunnel insulatingpattern 3 b, a charge-trap pattern 5 c, and a blocking insulatingpattern 17 a, may be formed under the word line 19 a and the firstspacers 21 a. The blocking insulating patterns 17 a and 17 b may bepartially damaged by the etching process. However, since the damagedsidewalls of the blocking insulating patterns 17 a and 17 b may beseparated from the lines 19 a and 19 b while contacting sidewalls of thespacers 21 a and 21 b, respectively, a breakdown current through thedamaged sidewalls of the blocking insulating patterns 17 a and 17 b maybe reduced during device operation.

When the driving gate line 19 b is a peripheral circuit gate electrode,the driving gate insulating layer 23 b may be referred to as aperipheral circuit gate insulating layer. When the driving gate line 19b is a selection line (such as a string selection line or a groundselection line) the driving gate insulating layer 23 b may be referredto as a selection gate insulating layer.

A charge-trap type non-volatile memory device according to someembodiments of the present invention will now be described withreference to FIG. 11. In the memory region, the charge-trap typepatterns 5 c may be isolated from each other by the device isolationlayers 13 b, and may individually exit in corresponding memory celltransistors. Accordingly, flow of charge trapped in one charge-trappattern 5 c to another charge-trap pattern 5 c of an adjacent celltransistor may be reduced, and threshold voltage drop may be reduced.Also, since the device isolation layer 13 may have a top surface whichis higher than or on the same level as a top surface of the charge-trappattern 5 c, concentration of an electric field at an edge of an activeregion may be reduced during device operation, thereby reducing currentleakage. Also, since the driving gate insulating layer 23 b in thedriving region does not include the charge-trap pattern 5 c, softprogramming of driving transistors may be reduced when the cell memorytransistors are programmed, and thus the driving transistors may bedriven at a relatively low voltage. As shown in FIG. 11, the drivinggate insulating layer(s) 23 b of FIG. 11 may be a double layer includingthe tunnel insulating pattern 3 b and the blocking insulating pattern 17b. If the tunnel insulating layer 3 a is removed in the driving regionas shown in FIG. 8, however, the driving gate insulating layer 23 b maybe a single layer including the blocking insulating pattern 17 b(without the tunnel insulating layer 3 b).

Also, the blocking insulating pattern 17 b may be formed of a highdielectric material, and the word line 19 a may be formed of a materialhaving a high work function, so that defective erase operations may bereduced.

A charge-trap type non-volatile memory device according to someembodiments of the present invention may thus provide improvedreliability.

In charge-trap type non-volatile memory devices, according to someembodiments of the present invention, charge-trap type patterns may beisolated from each other by the device isolation layers, and mayindividually exit in corresponding memory cell transistors. Accordingly,flow of charge trapped in one charge-trap pattern to another charge-trappattern of an adjacent cell transistor may be reduced. Also, since thedevice isolation layer may have a top surface which is higher than or onthe same level as a top surface of the charge-trap pattern,concentration of an electric field at an edge of an active region may bereduced during device operation, so that current leakage may be reduced.Also, since the driving gate insulating layer in the driving region maynot include the charge-trap pattern, soft programming of drivingtransistors may be reduced when the cell memory transistors areprogrammed, and thus the driving transistors may be driven at arelatively low voltage. Also, since the blocking insulating pattern maybe formed using spacers covering sidewalls of the word line as an etchmask, damaged portions of the blocking insulating pattern may notcontact the word line even though the sidewall portions thereof may bedamaged. Therefore, breakdown voltage may be reduced. Also, the blockinginsulating pattern may be formed of a high dielectric material, and theword line may be formed of a material having a high work function, sothat defective erase operations may be reduced. Accordingly, charge-traptype non-volatile memory devices according to some embodiments of thepresent invention may provide improved reliability.

While the present invention has been particularly shown and describedwith reference to embodiments thereof, it will be understood by those ofordinary skill in the art that various changes in form and details maybe made therein without departing from the spirit and scope of thepresent invention as defined by the following claims.

1. A method of forming a non-volatile memory device, the methodcomprising: forming a tunnel insulating layer on a semiconductorsubstrate; forming a charge-trap layer on the tunnel insulating layer;forming a trench extending through the tunnel insulating layer and thecharge-trap layer and into the semiconductor substrate so that portionsof the charge-trap layer and the tunnel insulating layers remain onopposite sides of the trench; forming a device isolation layer in thetrench; forming a blocking insulating layer on the device isolationlayer and on remaining portions of the charge-trap layer; forming a gateelectrode on the blocking insulating layer; and patterning the blockinginsulating layer and remaining portions of the charge-trap layer toprovide a blocking insulating pattern and a charge-trap pattern betweenthe gate electrode and the semiconductor substrate.
 2. A methodaccording to claim 1 wherein the blocking insulating layer comprises alayer of a material having a dielectric constant higher than that ofsilicon oxide.
 3. A method according to claim 1 wherein the gateelectrode comprises a material having a work function higher than thatof polysilicon.
 4. A method according to claim 1 wherein the gateelectrode comprises a metal.
 5. A method according to claim 1 furthercomprising: before forming the trench, forming a passivation layer onthe charge-trap layer and forming a planarization stop layer on thepassivation layer, wherein forming the trench further comprises formingthe trench through the planarization stop layer and the passivationlayer.
 6. A method according to claim 5 wherein forming the deviceisolation layer comprises, forming an insulating layer on remainingportions of the planarization stop layer and in the trench, planarizingthe insulating layer to expose the planarization stop layer whilemaintaining portions of the insulating layer in the trench, and removingthe planarization stop layer and the passivation layer.
 7. A methodaccording to claim 6 wherein removing the passivation layer comprisesremoving a portion of the device isolation layer.
 8. A method accordingto claim 1 wherein the charge-trap pattern is recessed relative to asurface of the device isolation layer opposite the substrate.
 9. Amethod according to claim 1, wherein the semiconductor substratecomprises a cell array region and a peripheral circuit region, themethod further comprising: before forming the blocking insulating layer,removing portions of the charge-trap layer on the peripheral circuitregion of the semiconductor substrate while maintaining portions of thecharge-trap layer on the cell array region of the semiconductorsubstrate.
 10. A method according to claim 1, further comprising: beforepatterning the blocking insulating layer and remaining portions of thecharge-trap layer, forming spacers on sidewalls of the gate electrode;wherein patterning the blocking insulating layer and remaining portionsof the charge-trap layer comprises patterning the blocking insulatinglayer and remaining portions of the charge-trap layer using the spacersas an etch mask.
 11. A method of forming a non-volatile memory device,the method comprising: forming a device isolation layer on portions of asemiconductor substrate separating first and second active regions ofthe semiconductor substrate on opposite sides of the device isolationlayer; forming first and second tunnel insulating patterns the on thefirst and second active regions of the semiconductor substrate; formingfirst and second charge-trap patterns on the respective first and secondtunnel insulating patterns wherein portions of the device isolationlayer between the first and second charge-trap patterns are free of thefirst and second charge-trap patterns; and forming a word line on thefirst and second charge-trap patterns and on portions of the deviceisolation layer between the first and second charge-trap patterns.
 12. Amethod according to claim 11 further comprising: forming a blockinginsulating layer on the first and second charge-trap patterns and on thedevice isolation layer so that the blocking insulating layer is betweenthe word line and the first and second charge-trap patterns and betweenthe word line and the device isolation layer.
 13. A method according toclaim 12 wherein the tunnel insulating layer comprises a layer of afirst insulating material having a first dielectric constant, whereinthe blocking insulating layer comprises a layer of a second insulatingmaterial having a second dielectric constant, and wherein the firstdielectric constant is less than the second dielectric constant.
 14. Amethod according to claim 11 wherein each of the first and secondcharge-trap patterns has a respective sidewall directly adjacentrespective sidewalls of the device isolation layer.
 15. A methodaccording to claim 11 wherein the word line comprises a material havinga work function higher than that of polysilicon.
 16. A method accordingto claim 11 wherein the word line comprises a material including ametal.
 17. A method according to claim 11 wherein a surface of thedevice isolation layer opposite the semiconductor substrate extends atleast as far from the semiconductor substrate as surfaces of thecharge-trap patterns opposite the semiconductor substrate.
 18. A methodaccording to claim 11 wherein the semiconductor substrate comprises acell array region and a peripheral circuit region and wherein the wordline is on the cell array region, the method further comprising: forminga peripheral circuit gate insulating layer on a peripheral circuitregion of the semiconductor substrate; forming a peripheral circuit gateelectrode on the peripheral circuit gate insulating layer so that theperipheral circuit gate insulating layer is between the peripheralcircuit gate electrode and the peripheral circuit region of thesemiconductor substrate, wherein a separation between the peripheralcircuit gate electrode and the peripheral circuit region of thesemiconductor substrate is less than a separation between the word lineand the first and second active regions of the semiconductor substrate.19. A method according to claim 11, further comprising: forming firstand second selection gate insulating patterns on the first and secondactive regions spaced apart from the first and second tunnel insulatingpatterns; forming a selection line on the first and second selectiongate insulting patterns and on portions of the device isolation layerbetween the first and second selection gate insulating patterns, whereina separation between the selection line and the first and second activeregions of the semiconductor substrate is less than a separation betweenthe word line and the first and second active regions of thesemiconductor substrate.
 20. A method according to claim 11, furthercomprising: forming spacers on sidewalls of the word line, wherein thefirst and second charge-trap patterns are between the spacers and thesemiconductor substrate in a direction perpendicular with respect to asurface of the semiconductor substrate.
 21. A non-volatile memory devicecomprising: a semiconductor substrate; a device isolation layer on thesemiconductor substrate separating first and second active regions ofthe semiconductor substrate on opposite sides of the device isolationlayer; first and second tunnel insulating patterns on the first andsecond active regions; first and second charge-trap patterns on therespective first and second tunnel insulating patterns wherein portionsof the device isolation layer between the first and second charge-trappatterns are free of the first and second charge-trap patterns; and aword line on the first and second charge-trap patterns and on portionsof the device isolation layer between the first and second charge-trappatterns.
 22. A non-volatile memory device according to claim 21 furthercomprising: a blocking insulating layer between the word line and thefirst and second charge-trap patterns and between the word line and thedevice isolation layer.
 23. A non-volatile memory device according toclaim 22 wherein the tunnel insulating layer comprises a layer of afirst insulating material having a first dielectric constant, whereinthe blocking insulating layer comprises a layer of a second insulatingmaterial having a second dielectric constant, and wherein the firstdielectric constant is less than the second dielectric constant.
 24. Anon-volatile memory device according to claim 21 wherein each of thefirst and second charge-trap patterns has a respective sidewall directlyadjacent respective sidewalls of the device isolation layer.
 25. Anon-volatile memory device according to claim 21 wherein the word linecomprises a material having a work function higher than that ofpolysilicon.
 26. A non-volatile memory device according to claim 21wherein the word line comprises a material including metal.
 27. Anon-volatile memory device according to claim 21 wherein a surface ofthe device isolation layer opposite the semiconductor substrate extendsat least as far from the semiconductor substrate as surfaces of thecharge-trap patterns opposite the semiconductor substrate.
 28. Anon-volatile memory device according to claim 21 wherein thesemiconductor substrate comprises a cell array region and a peripheralcircuit region and wherein the word line is on the cell array region,the non-volatile memory device further comprising: a peripheral circuitgate insulating layer on a peripheral circuit region of thesemiconductor substrate; a peripheral circuit gate electrode on theperipheral circuit gate insulating layer so that the peripheral circuitgate insulating layer is between the peripheral circuit gate electrodeand the peripheral circuit region of the semiconductor substrate,wherein a separation between the peripheral circuit gate electrode andthe peripheral circuit region of the semiconductor substrate is lessthan a separation between the word line and the first and second activeregions of the semiconductor substrate.
 29. A non-volatile memory deviceaccording to claim 28 further comprising: spacers on sidewalls of theperipheral circuit gate electrode, wherein the peripheral circuit gateinsulating layer is between the spacers and the semiconductor substratein a direction parallel with respect to a surface of the semiconductorsubstrate.
 30. A non-volatile memory device according to claim 21,further comprising: first and second selection gate insulating patternson the first and second active regions spaced apart from the first andsecond tunnel insulating patterns; a selection line on the first andsecond selection gate insulting patterns and on portions of the deviceisolation layer between the first and second selection gate insulatingpatterns, wherein a separation between the selection line and the firstand second active regions of the semiconductor substrate is less than aseparation between the word line and the first and second active regionsof the semiconductor substrate.
 31. A non-volatile memory deviceaccording to claim 30, further comprising: spacers on sidewalls of theselection line, wherein the first and second selection gate insulatingpatterns are between the spacers and the semiconductor substrate in adirection parallel with respect to a surface of the semiconductorsubstrate.
 32. A non-volatile memory device according to claim 21,further comprising: spacers on sidewalls of the word line, wherein thefirst and second charge-trap patterns are between the spacers and thesemiconductor substrate in a direction perpendicular with respect to asurface of the semiconductor substrate.